Sessile Drop Contact Angle Method Research Articles

Experimental Investigation of the Impact of CO2 Injection Strategies on Rock Wettability Alteration for CCS Applications

Carbon capture and storage (CCS) has been recognized as a pivotal technology for mitigating climate change by reducing CO2 emissions. Storing CO2 in deep saline aquifers requires preserving the water-wet nature of the formation throughout the storage period, which is crucial for maintaining rock integrity and storage efficiency. However, the wettability of formations can change upon exposure to supercritical CO2 (scCO2), potentially compromising storage efficiency. Despite extensive studies on various factors influencing wettability alteration, a significant research gap remains in understanding the effects of different CO2 injection strategies on wettability in deep saline formations (DSFs). This study addresses this gap by investigating how three distinct CO2 injection strategies—continuous scCO2 injection (CCI), water alternating with scCO2 injection (WAG), and simultaneous water and scCO2 injection (SAI)—affect the wettability of gray Berea sandstone and Indiana limestone, both selected for their homogeneous properties relevant to CCS. Using a standardized sessile drop contact angle method before and after CO2 injection, along with core flooding to model the injection process at an injection pressure of 1500 psi and temperature of 100 °F with a confining pressure of 2500 psi, the results indicate a shift in wettability towards more CO2-wet conditions for both rock types under all strategies with changes in CA of 61.6–83.4° and 77.6–87.9° and 81.5–124.2° and 94.6–128.0° for sandstone and limestone, respectively. However, the degree of change varies depending on the injection strategy: sandstone exhibits a pronounced response to the CCI strategy, with up to a 77% increase in contact angle (CA), particularly after extended exposure. At the same time, WAG shows the least change, suggesting that water introduction slows surface modification. For limestone, the changes in CA ranged from 9% to 49% across strategies, with WAG and SAI being more effective in altering its wettability. This study underscores the importance of selecting suitable CO2 injection strategies based on rock type and wettability characteristics to maximize carbon storage efficiency. The findings offer valuable insights into the complex interactions of fluid–rock systems and a guide for enhancing the design and implementation of CCS technologies in various geological settings.

Dynamic stabilization of formation fines to enhance oil recovery of a medium permeability sandstone core at reservoir conditions

Fines migration has impacted the efficiency of low salinity water flooding at reservoir condition. However, previous studies on the use of nanoparticles to combat this problem were not done at reservoir condition and the effect of porous media length was neglected. Hence, the objective of this study is to use mesoporous silica (SiO2) nanoparticles (MSNP) to stabilize formation fines to increase oil recovery during low salinity water flooding at reservoir condition. Likewise, effect of porous media length on dynamic retention of fines at high temperature high pressure (HTHP) reservoir condition was investigated. The breakthrough curves of reservoir fines adsorption by mesoporous SiO2 nanofluid (MSNF) were described using the Thomas and Yoon-Nelson models. Subsequently, the effect of reservoir fines stabilization on oil recovery was evaluated using a HTHP core flooding equipment. Also, the formation damage remediation propensity of MSNF was investigated. Finally, the oil recovery mechanism was determined using the sessile drop contact angle method. Experimental results of the dynamic adsorption with coefficient of determination (R2) values in the range of 0.967–0.999 signifies that the reservoir fines adsorption by MSNF were well predicted by Thomas and Yoon-Nelson models. Consequently, MSNF stabilized the reservoir fines by attaching onto their surface rather than on the porous media thereby changing the wettability to water-wet, decreasing the contact angle to 16.1°, 17.1° and 20.7° for kaolinite, illite and montmorillonite, respectively. Subsequently, increasing oil recovery by 22–23% original oil in place. Therefore, the use of MSNF to stabilize formation fines at reservoir condition is proffered.

Effects of mineral surface silanization and bitumen coating on its filtration from an aqueous slurry

The effects of residual bitumen on oil sands tailings filtration have rarely been examined. In the present work, the filtration of bitumen-coated minerals, including quartz, rutile, kaolinite, and montmorillonite, was studied. Bitumen-coated quartz was compared with silanized quartz to decouple the effects of surface hydrophobicity and adsorbed bitumen layer on filtration. The minerals were treated in bitumen-toluene solutions with different bitumen concentrations. The treated minerals were subjected to vaccum filtration and their wettability was measured by sessile drop contact angle method. It was found that the filtration rate of silanized quartz was linearly correlated with contact angle. It was also observed that at low bitumen concentration, the contact angle and filtration rate of all tested minerals were increased. However, at high bitumen concentration, the filtration rates were reduced drastically despite the high contact angle. CHNS elemental analyses, and X-ray photoelectron spectroscopy surface composition and depth profile analyses showed that the minerals had higher C, N, S contents and thicker bitumen layer when they were treated at higher bitumen concentration. It was hypothesized that under the pressure gradient during filtration, the thick and patchy bitumen coating layers could inter-penetrate when the mineral particles were pushed together, to form a inter-locked film to close off the pores in the filter cake. Indeed, mineral-bitumen aggregates were observed by X-ray microscope/nanoCT imaging of the filter cake. It was concluded that a thin layer of bitumen coating helped filtration due to the induced hydrophobicity, but a thick (and patchy) bitumen coating impeded filtration.

Effects of Heat Treatment on The Wettability and Color Properties of Betung Bamboo (Dendrocalamus Asper) Strand

Betung bamboo (Dendrocalamus Asper) has recently attracted interest as a sustainable reinforcement fiber in (polymer) composite materials. Utilization of bamboo has an advantages and disadvantages. It has a short growth cycle, lightweight, and good mechanical properties, but with poor wettability, dimensional instability, and low resistance againts biodeterioration agent. Some efforts have been devoted to alter and enhance its properties, especially wettability properties. Heat treatment under various temperature can enhance wettability properties due to chemical changes and migration of extractives, but also can induce color changes. Therefore, this study aims to investigate wettability properties and color changes of heat-treated Betung bamboo strand. The 1/3 middle of Betung bamboo was used as main material and converted into strand. Heat treatment temperatures applied were 140oC and 160oC for 3 hours. The wettability of Phenol Formaldehyde (PF) adhesive on heat treated Betung bamboo strand was measured using a sessile drop contact angle method. Constant contact angle and K-value were used as parameter of wettability. Color change of heat-treated Betung bamboo strand was measured by portable color difference meter model CDX 105 and characterized by CIE Lab. Results showed that the increasing temperature of heat treatment affected wettability and color properties. Contact angle tended to increase with an increase of temperature which is indicated an enhancement of wettability by making wood more hydrophobic. Increasing of temperature made Betung bamboo strand to be darker than that of control sample. Total color change (AE) values were 21.06 and 29.23 at 140 and 160 oC, respectively.

Existence of water repellency and its relation to structural stability of soils in a tropical Eucalyptus plantation forest

Water repellency is a globally well-known phenomenon in soils that is found to have direct or indirect impacts on vast majority of soil characteristics and dynamics. In this study, we aimed to examine the influence of soil water repellency on the structural stability of soils considering water stability of aggregates at the depths of 0–5, 5–10, 10–15, 15–20, and 20–25 cm. A Eucalyptus plantation forest characterized by steep slopes was selected for the study and the land was separated into three blocks (B1, B2, B3) considering the slope. The percentage of water stable aggregate (%WSA) was determined using a wet sieving apparatus. Water repellency in soils was examined using the water drop penetration time (WDPT) test and the sessile drop contact angle method. The water repellency and the organic matter content were highest in the topsoil (0–5 cm) and decreased with increasing soil depth showing strong negative exponential relationships. The clay content of B1 and B2 soils increased, and that of B3 decreased with increasing depth. The %WSA of the soils was very high showing >85% on the topsoil layer (0–5 cm), and >70% throughout the profile. Below 15 cm, B3 soils showed significantly higher water repellency compared with B1 and B2, however, showed no significant difference in %WSA compared with B1 and B2 soils. Although the primary cause of the reduction in the water repellency and %WSA with increasing soil depth seems to be the decrease in organic matter content, clay content can also be considered to have a pronounced influence. Despite the fact that the %WSA was very high on the surface, topsoil evidenced severe erosion corroborating that the improved stability of aggregate governed by water repellency does not necessarily lower the erosion. The %WSA might not be an effective indicator of the susceptibility to topsoil erosion in lands with steep slopes (>10°). Severe erosion in these sloped lands can be considered as resulted by the detachment of aggregates without disintegration, due to low cohesiveness and ease of detachment of aggregates as instigated by water-repellent conditions.

Application of polymeric nanofluid in enhancing oil recovery at reservoir condition

In this study, ascorbic acid was used to synthesize Cissus populnea nanoparticles (CPNP). The synthesized CPNP was isolated and the influence of the process variables on the physical properties were studied. The rheology of the formulated Cissus populnea nanofluid (CPNF) was measured and compared with Cissus populnea (CP) solution and commercial polymer xanthan. Moreover, the interfacial properties of CPNF were studied at various concentrations and temperatures, and the influence of salinity and their interaction with ultrasound was investigated. Sessile drop contact angle method was used to determine the wettability alteration efficiency of CPNF on an initially oil-wet sandstone core surface. Finally, CPNF and CP solutions were evaluated for EOR purposes at typical reservoir condition. The displacement process was scaled to reduce the number of parameters investigated using dimensionless parameters. The synthesis methods were efficient in generating sphere-shaped and elongated nanoparticles (50 nm mean diameter). Experimental results show that an increase in temperature of CP and CPNP yielded increased viscosity of the solutions in stark contrast to xanthan whose solution viscosity declines as the temperature increases. Besides, the CPNF was effective in lowering IFT at oil-water (O/W) interface and altered the wettability of the sandstone cores to water-wetting condition. The novel CPNF increased the oil recovery by 26% and was effective at high-temperature high-pressure (HTHP) reservoir condition. The result shows a transition from capillary dominated flow to gravity dominated flow as decrease in IFT decreased residual oil saturation and increased capillary and Bond number. The energy consumption and cost estimation of the proposed novel polymeric nanofluid shows it is cost-effective than conventional EOR chemicals.

Wettability and adherence of acrylic paints on long and short rotation teaks

ABSTRACT The quality of finished wood products depends on the quality of its coating layer. An important indicator for evaluating the quality is Adherence of the paint on the wood surface. The purpose of this research was to analyze the effect of wood surface roughness and the viscosity of acrylic paints (pure acrylic and acrylic copolymer) to the wettability and Adherence for long and short rotation teaks. Wood surface with various degrees of roughness was prepared by sanding with abrasive papers of P120, P240, and P360 grits. Different viscosity of the acrylic paints was prepared composition between paint and water (w/w) of 100:0, 90:10, 80:20, and 70:30. The wettability of the acrylic paints on teak wood surfaces was measured using a sessile drop contact angle method with the S/G model. Adherence of the coating layer was measured using a crosscut test. The results showed that the increase in the roughness (Ra) and the decrease in the viscosity of the paints resulted in the increase in the wettability which leads to better Adherence of acrylic paints on the surface of teak woods. The pure acrylic paint generated better wettability and Adherence compared to the acrylic copolymer.

Wettability and bonding quality of exterior coatings on jabon and sengon wood surfaces

Wettability and bonding quality of exterior coatings on fast-growing wood surfaces were studied. Samples of air-dried flat-grained (tangential surface) and edge-grained (radial surface) pattern of jabon (Anthocephalus cadamba) and sengon (Paraserianthes falcataria) woods were used. Before application of exterior coatings, the surfaces of the lumber samples were sanded. To provide wood surfaces with various degrees of roughness, abrasive papers of 120, 240, and 360 grits were used for the surface preparation. The wettability of two exterior coatings (water-based acrylic and oil-based alkyd varnishes) on the sanded wood surfaces was measured using a sessile drop contact angle method. The Shi and Gardner (S/G) model was used to evaluate and compare the wettability of the surface coatings on the wood. The sanded wood samples were coated with the two coatings (two layers each). Bonding quality of the coating layers was measured using a crosscut tape test method. Experimental results show that constant contact angle change rate (K value) of the S/G model decreased as the grit number of abrasive paper increased. This indicates that the wettability decreased as the roughness of the surface decreased (surface becomes smoother). There was no evidence of differences in wettability between tangential and radial wood surfaces. The oil-based alkyd coating generated better wettability compared to the water-based acrylic. The crosscut tests showed that the bonding quality of the coating films on both jabon and sengon wood decreased as the surface became smoother. The sengon wood compared to jabon wood provided better coating wettability and bonding quality. Wettability in terms of the K values was a good indication for determining the bonding quality of the two varnish layers.

Irreversible sorption of humic substances causes a decrease in wettability of clay surfaces as measured by a sessile drop contact angle method

The objective of the study was to obtain quantitative assessments of the hydrophobic impact of irreversible sorption of humic substances (HSs) onto clay mineral surfaces using a sessile drop contact angle method. Two clays (kaolin and montmorillonite) were modified with four humic materials: (1) sod podzolic soil, (2) chernozem, (3) peat, and (4) coal (leonardite). The humic materials were characterized using elemental analysis, size exclusion chromatography, and 13C NMR spectroscopy. Both clay samples were saturated with Ca2+ prior to modification with HS using a sorption isotherm technique. Contact angles (CAs) of the obtained HS-clay complexes were determined using a static sessile drop method after drying the obtained HS-clay complexes in the form of a thin film. HS modification rendered both clays under study—kaolin and montmorillonite—more hydrophobic. In case of Ca-kaolin, the CA values increased from 27° (Ca-kaolin) up to 31°–32° (all HS-kaolin complexes) with no significant difference among the HS types used for modification. In the case of Ca-montmorillonite, the CA values increased from 41° (Ca-montmorillonite) up to 51°–83° with the following ascending trend for the humic types investigated: chernozem HS < coal HS < peat HS < sod-podzolic HS. This trend is in reverse to the degree of aromaticity of the HS, expressed as the content of aromatic carbon, and it is directly proportional to the molecular weight of each HS. Application of a sessile drop method showed increased surface hydrophobicity of HS-modified clays. Much more substantial hydrophobization was observed for montmorillonite as compared to kaolin, which was explained by the differences in the sorption mechanism.

Self-bonded composite films based on cellulose nanofibers and chitin nanocrystals as antifungal materials

Cellulose nanofibers and chitin nanocrystals, two main components of agricultural and aquacultural by-products, were obtained from blue agave and yellow squat lobster industrial residues. Cellulose nanofibers were obtained using high pressure homogenization, while chitin nanocrystals were obtained by hydrolysis in acid medium. Cellulose nanofibers and chitin nanocrystals were characterized by X-ray diffraction, Atomic Force Microscopy and Infrared spectroscopy. Self-bonded composite films with different composition were fabricated by hot pressing and their properties were evaluated. Antifungal activity of chitin nanocrystals was studied using a Cellometer® cell count device, mechanical properties at tension were measured with a universal testing machine, water vapor permeability was evaluated with a thermohygrometer and surface tension with sessile drop contact angle method. The addition of chitin nanocrystals reduced slightly the mechanical properties of the composite. Presence of chitin nanocrystals influenced the growth of Aspergillus sp fungus in the surface of the composites as expected.

Surface Modification of Silicate Glass Using 3-(Mercaptopropyl)trimethoxysilane for Thiol–Ene Polymerization

A thiol-ene polymerization was accomplished on silicate glass slides to graft a series of homopolymers and copolymers using 3-(mercaptopropyl)trimethoxysilane (MTS) as both a silane coupling agent and initiator. MTS was initially covalently bonded to an acid cleaned glass surface via a classical sol-gel reaction. Poly(acrylic acid) (PAA), poly(acrylamide) (PAAm), poly(methyl acrylate) (PMA), poly(acrylamido-2-methyl-propanesulfonic acid) (PAMPS), and the copolymer poly(AA-co-AAm-co-MA-co-AMPS) were grafted from the thiol group of MTS. The surface chemistry of the MTS modified slides and polymer grafts was characterized with attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Surface texture was evaluated with tapping mode atomic force microscopy (TM-AFM). The Owens-Wendt-Kaelble (OWK) and Lifshitz-van der Waals acid-base (LW-AB) methods were used to evaluate surface energies by sessile drop contact angle method. The synthetic approach demonstrated a facile, rapid method for grafting to glass surfaces.

Thermal treatment of Nigerian-grownAlbizziazygiaandFuntumiaelasticawood in soy oil medium Part 2: Effects on hygroscopic, swelling and surface properties

Thermal treatment in soy oil medium is one of the techniques used as a substitute for chemical treatment in wood preservation. However, the effects of this technique vary from one species to another and hence the need to investigate the response of individual species to it. Thermal treatment of air-dried Nigerian-grown Albizzia zygia and Funtumia elastica wood was carried out in a vessel containing soy oil at a temperature of 220°C for 2hours. This was followed by the determination of hygroscopy and swelling by water soaking method; surface energy by the sessile drop contact angle method; pH and buffer capacity by the cold extraction method. The process of soy oil thermal treatment resulted in significant reductions in hygroscopy, swelling properties and pH in both species with accompanying increase in buffer acid and alkaline buffer capacity. The surface energy which is an indication of wettability was reduced in Albizzia zygia but increased in Funtumia elastica. The reductions in hygroscopy and pH are indications of cellulose degradation during the heat treatment process leading to build up of acid formation. The reduction in hygroscopic behaviour indicates potential for stability in wood-water relationship especially when the material will be used in a continuously-changing ambient environment. The reduction in surface energy in Albizzia zygia implies that soy-oil-thermally modified wood from this species will have reduced interfacial attractions with most chemical adhesives. On the other hand, the increase in surface energy in Funtumia elastica shows possibility of improvement in the level of interfacial attractions between wood (substrates) and adhesives. The reduction in pH in both species is expected to have a two-way effect; a benefit through reduction in adhesive curing time and an adverse effect through expected reduction in strength properties.

Water infiltration and hydrophobicity in forest soils of a pine–beech transformation chronosequence

Summary Soil water repellency is widespread in forest soils and has important hydrological implications. The relation of soil water repellency to hydraulic properties is of interest to assess the overall hydrological behaviour of a forest ecosystem. Both soil water repellency and hydraulic properties depend on tree species and age, forest management practices, and the season of the year. In this study, the variation of soil water repellency and hydraulic properties during the season of the year and between different forest stands are analysed for a pine–beech forest transformation chronosequence. Soil water repellency is assessed with the water drop penetration time (WDPT) test, the critical surface tension (CST) test, and the sessile drop contact angle method. Hydraulic conductivity is measured with a hood infiltrometer, a special form of a tension infiltrometer, and a ponded ring infiltrometer. Soil water repellency for the upper 10 cm of the soil exhibited a pronounced seasonal variability, both for field moist and oven dry samples, whereas the variability between the different forest transformation stages seemed to be less significant. For hydraulic parameters, the differences between the forest stands and the measurement dates were lower than the variabilities within the stands and within the dates, but also the hydraulic conductivities revealed a seasonal trend with higher values during the summer months. Saturated hydraulic conductivities determined with the hood infiltrometer were by a factor of 10 lower than saturated hydraulic conductivities estimated with the ponded ring infiltrometer. Presumably, Ks values estimated with the hood infiltrometer are underestimated due to an incomplete wetting of the soil beneath the infiltrometer. This would limit the suitability of this device for water repellent soils, unless the soil is thoroughly wetted prior to infiltration measurements.

Functional Properties of Edible Agar-Based and Starch-Based Films for Food Quality Preservation

Edible films made of agar (AG), cassava starch (CAS), normal rice starch (NRS), and waxy (glutinous) rice starch (WRS) were elaborated and tested for a potential use as edible packaging or coating. Their water vapor permeabilities (WVP) were comparable with those of most of the polysaccharide-based films and with some protein-based films. Depending on the environmental moisture pressure, the WVP of the films varies and remains constant when the relative humidity (RH) is >84%. Equilibrium sorption isotherms of these films have been measured; the Guggenheim-Anderson-de Boer (GAB) model was used to describe the sorption isotherm and contributed to a better knowledge of hydration properties. Surface hydrophobicity and wettability of these films were also investigated using the sessile drop contact angle method. The results obtained suggested the migration of the lipid fraction toward evaporation surface during film drying. Among these polysaccharide-based films, AG-based film and CAS-based film displayed more interesting mechanical properties: they are transparent, clear, homogeneous, flexible, and easily handled. NRS- and WRS-based films were relatively brittle and have a low tension resistance. Microstructure of film cross section was observed by environmental scanning electron microscopy to better understand the effect of the structure on the functional properties. The results suggest that AG-based film and CAS-based films, which show better functional properties, are promising systems to be used as food packaging or coating instead of NRS- and WRS-based films.

Surface condition effects of the inter-metal dielectrics on interconnect aluminum film properties

Surface quality and optical reflectivity of the hot-Al/Ti interconnecting metal layers show a strong dependence on the surface condition of the underlying inter-metal dielectric oxides (IMDs). When hot-Al/Ti films are deposited by a two-step method, a much lower (0002) Ti X-ray diffraction is obtained from the hydrophilic oxide substrates than from the hydrophobic ones. This Ti film crystalline structure affects (111) diffraction and surface roughness of the Al interconnecting films. An optimized RF pre-cleaning process prior to the Al/Ti deposition enhances the smoothness and hydrophobic surface property of the IMDs, as measured by atomic force microscopy and sessile drop contact angle method, and greatly improves aluminum surface quality. Etch yield of the interconnect lines is monitored at 0.4/0.4 μm bridge test patterns of 3.5 mega-bit arrays, and is greatly influenced by the surface condition of underlying IMDs.

Development and application of a new sessile drop contact angle method to assess soil water repellency

Existing methods for determining the contact angle as a measure of the water repellency of soils are either indirect, or cumbersome and time-consuming. Our objective was to develop a new method that is simpler than the existing procedures like the capillary rise method and that still yields accurate and reproducible results. To this end, we applied the so-called sessile drop method. To obtain the needed plane sample surface and to reduce geometrical effects, a single layer of air-dry soil particles is sprinkled on double-sided adhesive tape. Eight droplets of deionized water are placed carefully on this horizontal particle layer. Immediately after sample preparation, the contact angle at the three-phase boundary was measured with a goniometer-fitted microscope. In order to test the new method, contact angle measurements were carried out with wettable soil material that was hydrophobized, and with soils showing a wide range of natural water repellency. Both wettable silt and sand were made hydrophobic with Dimethyldichlorosilane and diluted with untreated soil to obtain a defined variation in the solid surface tension. Contact angle measurements showed a nonlinear decrease with increasing amounts of wettable particles in the 40–90° contact angle domain. Generally, the contact angle decrease was predictable and could be described with an empirical model. For volcanic ash soils showing a wide range of repellency, the contact angles of different, narrowly sieved soils fractions (<20μm, 20–38μm, 38–63μm, and 63–100μm) were within the range of 25–110°. The impact of the different sieved soil fractions on the contact angles was found to be small. Measurements performed with independent replicates showed good reproducibility across the whole range of contact angles.